Wire splicing device, wire splicing method, and method for manufacturing splice structure

ABSTRACT

A wire splicing method including: disposing a tape-like first wire and a tape-like second wire in a holding base so that an end portion of the first wire and an end portion of the second wire face each other; disposing solder to straddle the first wire and the second wire; disposing a connection wire on the solder; pressing a heating body to the first wire, the second wire, and the connection wire via a pressing plate, and pressing together and heating the first wire, the second wire, and the connection wire so as to melt the solder; keeping the first wire, the second wire, and the connection wire pressed together by the pressing plate; separating the heating body from the pressing plate; and cooling the pressing plate to solidify the solder, and thereby connecting the first wire and the second wire together.

This application is a Divisional of U.S. application Ser. No.14/893,814, filed on Nov. 24, 2015, claiming priority from JapanesePatent Application No. JP 2013-112141, filed on May 28, 2013, whichclaims priority from PCT/JP2014/064184, filed on May 28, 2014. Theentire disclosures of the prior applications are considered part of thedisclosure of the accompanying continuation application, and are herebyincorporated by reference.

TECHNICAL FIELD Background Art

In order to use a wire such as a superconducting wire in a device, thereis an increasing demand for a connection technique for connecting wireswith solder. For example, PTL 1 discloses a connection device 100 whichconnects superconducting wires together (see FIG. 5). The connectiondevice 100 includes a lower pressing and heating plate 101B providedwith a wire accommodation groove 102 having substantially the same widthas that of a wire, and an upper pressing and heating plate 101A providedwith a protrusion 112A having a slightly smaller width than that of thewire accommodation groove 102, and is configured so that the opening ofthe lower pressing and heating plate 101B is covered with the upperpressing and heating plate 101A by an opening and closing mechanism 108and thus heating and pressing can be performed on the wire. When thewires are bonded together, the end portions of the wires areaccommodated in the wire accommodation groove 102 in an overlappingmanner with solder interposed therebetween, and as pressing together andheating are performed by the lower pressing and heating plate 101B andthe upper pressing and heating plate 101A, the solder is melted toconnect the superconducting wires.

Since the connection device 100 is used, an operator does not need tomelt the solder by using a soldering iron in order to connect thesuperconducting wires. That is, it is possible to form a splicestructure that exhibits stable connection performance regardless of theskill of the operator.

PRIOR ART DOCUMENTS Patent Documents

[PTL 1] Japanese Unexamined Patent Application, First Publication No.2011-3382

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

In the connection device 100 described in PTL 1, heat and pressure areapplied to the wires by the pair of heating and pressing plates 101A and101B provided with both a heating member and a pressing unit. Therefore,in a case where the connection device 100 is used, there is a need tocool the heating member (for example, a heater) itself in order tosolidify the solder at the connection portion. Therefore, a long time isneeded to make the connection. In addition, when a connection operationis continuously performed using the same device, the cooled heater needsto be re-heated, and thus a long time is needed to sufficiently heat upthe heater. Therefore, there is a problem in that the productionefficiency is poor.

The present invention has been made taking the foregoing circumstancesinto consideration, and an object thereof is to provide a wire splicingdevice which enables connection of wires that exhibit stable performancewith high production efficiency, a wire splicing method, and a methodfor manufacturing a splice structure.

Means for Solving the Problems

According to a first aspect of the present invention, there is provideda wire splicing device including: a holding base which is provided witha wire accommodation groove having a width, the wire accommodationgroove being configured to accommodate a plurality of wires; a pressingplate which is positioned above the holding base; a heating body whichis positioned above the pressing plate and includes a heating member; afirst driver which drives the holding base and the pressing plate towardor away from one another; and a second driver which drives the holdingbase and the heating body toward or away from one another, in which thepressing plate which is driven toward the holding base by the firstdriver presses together the plurality of wires accommodated in the wireaccommodation groove with solder interposed therebetween, and theheating body which is driven toward the holding base by the seconddriver presses together and heats, via the pressing plate, the pluralityof wires accommodated in the wire accommodation groove with soldertherebetween.

In the wire splicing device according to the first aspect, the pressingplate which presses a connection portion of the wires and the heatingbody which heats the connection portion are separately provided, and thepressing plate and the heating body can be separately driven toward andseparated from the connection portion of the wires by the first driverand the second driver. Therefore, the connection portion of the wires isheated by the heating body via the pressing plate so as to melt thesolder, the heating body is thereafter separated from the pressing plate(that is, separated from the wires) while continuing to be pressed bythe pressing plate, and heating of the wires can be immediately stopped.Accordingly, the wires are not continuously heated until the heatingbody has been cooled, and the time required to solidify the solder isreduced. Therefore, the time needed to make the connection is reduced.

The wire splicing device according to the first aspect can be used toconnect tape-like superconducting wires represented by a Bi-based orRE-123-based superconducting wire. There may be a case where thesuperconducting properties of the superconducting wires may deterioratedue to heat. However, the wire splicing device according to the firstaspect can limit the deterioration of the superconducting wires byreducing the heating time. In addition, there may be a case where aprotection layer made of silver or a silver alloy is provided on theouter periphery of the superconducting wire. The protection layerfunctions as a bypass in a case where the superconducting state of thesuperconducting wire has collapsed, and thus preferably has lowresistance. When the heating time during the connection is lengthened,solder in the protection layer diffuses and may form an alloy of solderand silver. The alloy of solder and silver has high electricalresistance and does not allow functions as bypasses to be sufficientlyexhibited. The wire splicing device according to the first aspect canlimit the diffusion of the solder to the protection layer by reducingthe heating time.

In the wire splicing device according to the first aspect, since heatingthe connection portion of the wires is started or stopped by bringingthe heating body into contact with the pressing plate or separating ittherefrom, the heating body can always be held at a temperature at whichthe solder melts. Therefore, in a case where a subsequent connectionoperation is consecutively performed, the heating body does not need tobe re-heated, and the time it takes to increase the temperature of theheating body to a temperature at which the solder is melted can bereduced.

Furthermore, a plate-like pressing plate has a large surface area, hashigh heat dissipation properties, and thus can quickly reduce thetemperature of the connection portion, and thereby reduce the timeneeded to solidify the solder. That is, the production efficiency can beimproved.

In addition, in the first aspect, the holding base may be made of aninsulating material.

In this case, since the holding base is made of the insulating material,an increase in the temperature of the holding base is suppressed evenwhen a bonding portion of the wires is heated, and thus thesolidification of the solder is not impeded during cooling, and therebythe production efficiency is increased.

In addition, the wire splicing device in the first aspect may furtherinclude a cooling member which cools the pressing plate.

In the case where the cooling member which cools the pressing plate isincluded, in a state where the heating body is separated from thepressing plate after the solder is melted, the pressing plate can berapidly cooled. Therefore, the time needed to solidify the solder of theconnection portion is reduced, and thereby the production efficiency isincreased.

In addition, in the first aspect, the first driver may be a first aircylinder which raises and lowers the pressing plate (moves the pressingplate up and down), and the second driver may be a second air cylinderwhich raises and lowers the heating body (moves the heating body up anddown).

Since the air cylinders are used as the first driver and the seconddriver, the wires can be pressed together at a predetermined pressure,and thus the breaking of the wires can be limited.

According to a second aspect of the present invention, there is provideda wire splicing method including: disposing an end portion of atape-like first wire and an end portion of a tape-like second wire in aholding base in an overlapping manner via solder (wire disposingprocess), pressing a heating body to the first wire and the second wirevia a pressing plate, and pressing together and heating the first wireand the second wire so as to melt the solder (pressing together andheating process); and keeping the first wire and the second wire pressedtogether using the pressing plate, separating the heating body from thepressing plate, and cooling the pressing plate to solidify the solder,and thereby connect the first wire and the second wire together (coolingprocess).

According to a third aspect of the present invention, there is provideda wire splicing method including: disposing a tape-like first wire and atape-like second wire in a holding base so that an end portion of thefirst wire and an end portion of the second wire oppose each other;disposing solder to straddle the first wire and the second wire;disposing a connection wire on the solder (wire disposing process);pressing a heating body to the first wire, the second wire, and theconnection wire via a pressing plate, and pressing together and heatingthe first wire, the second wire, and the connection wire so as to meltthe solder (pressing together and heating process); and keeping thefirst wire, the second wire, and the connection wire pressed togetherusing the pressing plate, separating the heating body from the pressingplate, and cooling the pressing plate to solidify the solder, andthereby connect the first wire and the second wire together (coolingprocess).

According to the wire splicing method according to the second or thirdaspect, since the wire splicing device is used, connection of wires thatexhibit stable performance is enabled with high production efficiency.

In addition, in the second or the third aspect, the first wire and thesecond wire may be superconducting wires.

In addition, in the third aspect, the first wire, the second wire, andthe connection wire may be superconducting wires.

In this case, heat is not excessively applied to the superconductingwires, and the first wire and the second wire can be connected togetherby being heated for a short amount of time. Therefore, deterioration inthe properties of the superconducting wires during the connection can belimited.

In a fourth aspect of the present invention, there is provided a methodfor manufacturing a splice structure including: disposing an end portionof a tape-like first wire and an end portion of a tape-like second wirein a holding base in an overlapping manner via solder; pressing aheating body to the first wire and the second wire via a pressing plate,and pressing together and heating the first wire and the second wire soas to melt the solder; and keeping the first wire and the second wirepressed together by the pressing plate, separating the heating body fromthe pressing plate, and cooling the pressing plate to solidify thesolder, and thereby connect the first wire and the second wire together.

In a fifth aspect of the present invention, there is provided a methodfor manufacturing a splice structure including: disposing a tape-likefirst wire and a tape-like second wire in a holding base so that an endportion of the first wire and an end portion of the second wire tooppose each other; disposing solder to straddle the first wire and thesecond wire; disposing a connection wire on the solder; pressing aheating body to the first wire, the second wire, and the connection wirevia a pressing plate, and pressing together and heating the first wire,the second wire, and the connection wire so as to melt the solder; andkeeping the first wire, the second wire, and the connection wire pressedtogether by the pressing plate, separating the heating body from thepressing plate, and cooling the pressing plate to solidify the solder,and thereby connecting the first wire and the second wire together.

In addition, in the fourth or the fifth aspect, the first wire and thesecond wire may be superconducting wires.

In addition, in the fifth aspect, the first wire, the second wire, andthe connection wire may be superconducting wires.

In this case, heat is not excessively applied to the superconductingwires, and the first wire and the second wire can be connected togetherby heating for a short amount of time. Therefore, deterioration in theproperties of the superconducting wires during the connection can belimited.

Effects of the Invention

According to the wire splicing device, the wire splicing method, and themethod for manufacturing a splice structure according to the aboveaspects, the pressing plate which presses together the connectionportion of the wires and the heating body which heats the connectionportion are separately provided, and the pressing plate and the heatingbody can be separately driven towards and separated from the connectionportion of the wires by the first driver and the second driver.Therefore, the connection portions of the wires is heated by the heatingbody via the pressing plate so as to melt the solder, the heating bodyis thereafter separated from the pressing plate (that is, separated fromthe wires) while the pressing plate continues to press together theconnection portions of the wires, and heating of the wires can beimmediately stopped. Accordingly, the wires are not continuously heateduntil the heating body is cooled, and the time required to solidify thesolder is reduced. Therefore, a time required to make the connection isreduced. Furthermore, the plate-like pressing plate has a large surfacearea, has high heat dissipation properties, and thus can quickly reducethe temperature of the connection portion, and thereby reduce the timeneeded to solidify the solder. That is, the production efficiency can beimproved.

In addition, according to the wire splicing device, the wire splicingmethod, and the method for manufacturing a splice structure according tothe above aspects, since heating the connection portion of the wires isstarted or stopped by bringing the heating body in contact with orseparating the heating body from the pressing plate, the heating bodycan be always held at a temperature at which the solder is melted.Therefore, in a case where a subsequent connection operation isconsecutively performed, the heating body does not need to be re-heated,and the time it takes to increase the temperature of the heating body tothe temperature at which the solder is melted can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a side view showing a wire splicing device according to anembodiment of the present invention.

FIG. 1B is a front view showing the wire splicing device according tothe embodiment of the present invention.

FIG. 2A is a view showing a first splice structure of wires formed bythe wire splicing device according to the embodiment of the presentinvention.

FIG. 2B is a view showing a second splice structure of wires formed bythe wire splicing device according to the embodiment of the presentinvention.

FIG. 3 is a schematic sectional view of a connection portion when thewires are connected together by using the wire splicing device accordingto the embodiment of the present invention.

FIG. 4A is a view showing the order in which the wires are connectedtogether by using the wire splicing device according to the embodimentof the present invention, and the wires to be connected being providedwith solder interposed therebetween in a wire accommodation groove of aholding base.

FIG. 4B is a view showing the order in which the wires are connectedtogether by using the wire splicing device according to the embodimentof the present invention, and a connection portion of the wires beingpressed by a pressing plate.

FIG. 4C is a view showing the order in which the wires are connectedtogether by using the wire splicing device according to the embodimentof the present invention, and the connection portion of the wires beingheated by a heating body via the pressing plate to solidify the solder.

FIG. 4D is a view showing the order in which the wires are connectedtogether by using the wire splicing device according to the embodimentof the present invention, and the heating body being separated from thepressing plate so as to allow the pressing plate to be cooled by anair-cooling fan.

FIG. 4E is a view showing the order in which the wires are connectedtogether by using the wire splicing device according to the embodimentof the present invention, and the solidification of the solder beingcompleted and the pressing plate being separated from the connectionportion.

FIG. 5 shows an example of a wire splicing device according to therelated art.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an embodiment of a wire splicing device according to thepresent invention will be described with reference to the drawings.There is a case where, in the drawings referred to in the followingdescription, featured parts are exaggerated in order to facilitateunderstanding thereof, and the dimensional ratios and the like ofconstituent elements are not limited to being the same as actual ones.In addition, the present invention is not limited to the followingembodiment.

(Wire Splicing Device)

FIGS. 1A and 1B show a side view and a front view of a wire splicingdevice 1 according to the embodiment of the present invention.

The wire splicing device 1 includes a holding base 7 on which wires tobe connected are placed, a pressing plate 5 disposed above the holdingbase 7, and a heating body 4 further disposed above the pressing plate5.

The holding base 7 is a rectangular parallelepiped-shaped base, and anupper surface 7 b thereof is formed in a substantially rectangular shapehaving a long side in a direction coincident with the longitudinaldirection of the wires to be connected. In the upper surface 7 b, a wireaccommodation groove 7 a is formed to accommodate the wires along theoverall length of the holding base 7 in the longitudinal directionthereof. It is preferable that the depth of the wire accommodationgroove 7 a be substantially the same as or greater than the sum of thethicknesses of the overlapping portions of the pair of wires to beconnected and the thickness of the solder.

Since the width of the wire accommodation groove 7 a is substantiallythe same as the width of the wire, by disposing the wires in anoverlapping manner with the solder interposed therebetween in the wireaccommodation groove 7 a and allowing the solder to be melted andsolidified, a splice structure in which the wires are not misalignedfrom each other can be formed. In addition, the molten solder does notprotrude from the side surface of the wires. Therefore, the widthdimensions of the connection portion and non-connection portions are notdifferent from each other, and there is no inconvenience during handlingof the connection portion.

In addition, clamping mechanisms (not shown) which hold the wires mayalso be provided in the vicinity of both end portions of the wireaccommodation groove 7 a in the longitudinal direction thereof. In acase where the clamping mechanisms are provided, the wires can be heldby the clamping mechanisms in a state where the wires are disposed inthe wire accommodation groove 7 a. Therefore, misalignment of the wiresin the longitudinal direction thereof can be reliably limited, and thusa portion (the connection portion) in which the wires overlap and arebonded together by the solder can be formed of a predetermined length.

The pressing plate 5 is made of a thin plate material formed in arectangular shape having a long side in the same direction as the longside of the upper surface 7 b of the holding base 7, and is formed to befurther smaller than the upper surface 7 b of the holding base 7.

An upper surface 5 b of the pressing plate 5 is formed to be flat toensure a contact surface between the upper surface 5 b and a lowersurface 4 a of the heating body 4 which is also formed to be flat.

In addition, the center portion of the lower surface of the pressingplate 5 is provided with a rectangular parallelepiped-shaped protrusion5 a having a slightly smaller width than the width of the wireaccommodation groove 7 a of the holding base 7. The protrusion 5 a andthe wire accommodation groove 7 a are configured to be fitted with eachother without causing misalignment in position when the holding base 7and the pressing plate 5 overlap each other.

In this embodiment, the height of the protrusion 5 a is formed to besubstantially the same as the depth of the wire accommodation groove 7a. However, the height is not particularly limited when the height isformed such that the wires to be connected are accommodated in the wireaccommodation groove 7 a with the solder interposed therebetween and inthis state, the upper surfaces of the wires of the connection portioncan be pressed.

In addition, in this embodiment, the length of the protrusion 5 a in thelongitudinal direction thereof is a length of about ⅔ of the overalllength of the wire accommodation groove 7 a, and is not particularlylimited when the length is equal to or greater than the length of theportion where the wires to be connected overlap each other.

The heating body 4 disposed above the pressing plate 5 has a block shapeof which the longitudinal direction is a direction coincident with thelongitudinal direction of the pressing plate 5. The heating body 4includes a heating member and thus can heat the solder of the connectionportion to its melting point or higher via the pressing plate 5. Theconfiguration of the heating member is not concerned as long as theheating member is a device capable of heating the lower surface 4 a ofthe heating body 4 to the melting point of the solder or higher, and acurrent-carrying type electric heater or the like may be used. The lowersurface 4 a of the heating body 4 is formed to be flat and is configuredto transfer heat of the heating body 4 by coming into surface contactwith the upper surface 5 b of the pressing plate 5. The lower surface 4a of the heating body 4 is configured to cover the projection area ofthe protrusion 5 a of the pressing plate 5, and accordingly, canimmediately heat the connection portion of the wires via the protrusion5 a.

First rods 2A that extend in a vertical direction are respectivelyattached to two corners of the upper surface 5 b of the pressing plate 5on one long side among the four corners of the upper surface 5 b. Thepressing plate 5 is held by the pair of first rods 2A and 2A. The pairof first rods 2A and 2A are connected to a first air cylinder (firstdriver) 2 by penetrating therethrough, and the pressing plate 5 can beelevated in the vertical direction by the first air cylinder 2. Inaddition, since the pair of first rods 2A and 2A are driven insynchronization with each other, the pressing plate 5 performs parallelmovement in the vertical direction.

Similarly, second rods 3A that extend in the vertical direction arerespectively attached to the vicinities of both end portions of theupper surface of the heating body 4 in the longitudinal direction of theheating body 4. The heating body 4 is held by the pair of second rods 3Aand 3A. The pair of second rods 3A and 3A are connected to a second aircylinder (second driver) 3 by penetrating therethrough, and the heatingbody 4 can be elevated in the vertical direction by the second aircylinder 3. In addition, since the pair of second rods 3A and 3A aredriven in synchronization with each other, the heating body 4 performsparallel movement in the vertical direction.

A tube (not shown) through which compressed air is supplied is connectedto the first air cylinder 2 and the second air cylinder 3, and the firstrods 2A and 2A or the second rods 3A and 3A are driven in the verticaldirection by air pressure.

In addition, the first air cylinder 2 and the second air cylinder 3 arefixed so that the relative distances from the holding base 7 do notchange, and fixing units are omitted in FIGS. 1A and 1B.

An air-cooling fan (cooling member) 6 is installed on the long side edgeportion of the upper surface 7 b of the holding base 7 so as to avoidthe movement ranges of the pressing plate 5 and the heating body 4. Theair-cooling fan 6 is installed for the purpose of air-cooling thepressing plate 5 in a state where the pressing plate 5 is lowered tooverlap the holding base 7, and is configured to blow air toward theupper surface 5 b of the pressing plate 5 in the lowered state.

It is preferable that the blowing opening of the air-cooling fan 6 isconfigured to have substantially the same length as the long side lengthof the upper surface 5 b of the pressing plate 5 so as to air-cool theentirety of the upper surface 5 b of the pressing plate 5.

The wire splicing device 1 of this embodiment is schematicallyconfigured as described above. Hereinafter, each of the constituentparts of the wire splicing device 1 will be described in more detail.

As the material of the holding base 7 which becomes the base on whichthe wires are disposed, an insulating material which is made of ceramicor the like and has low thermal conductivity and high insulatingproperties is preferably used. Accordingly, an increase in thetemperature of the holding base 7 is suppressed, and thus thesolidification of the solder is not impeded, and thereby increasesproduction efficiency.

As the ceramic that can be used as the material of the holding base 7,for example, a machineable ceramic having high insulating properties andhigh machinability, such as Macor and Photoveel (registered trademarks),may be appropriately used.

The pressing plate 5 exhibits a function of suppressing misalignmentbetween the wires to be connected in the longitudinal direction of thewires (clamping function) and a function of transferring heat of theheating body 4 to the bonding portion of the wires. Therefore, it ispreferable that the pressing plate 5 has a strength with which theconnection portion of the wires can be sufficiently pressed and has amaterial and a shape such that heat from the heating body 4 can besufficiently transferred to the connection portion of the wires.

In addition, the pressing plate 5 has a function of accelerating thecooling of the solder of the bonding portion of the wires by ensuring aheat dissipation area. Therefore, it is preferable that the pressingplate 5 is made of a material having high heat dissipation properties.Specifically, it is preferable that a metal material having a thicknessof 1 mm to 10 mm is used. As the metal material, stainless steel or thelike is used. Otherwise, a material having a high thermal conductivityand heat transfer coefficient, such as aluminum, copper, and an alloythereof, is appropriately used.

Since the pressing plate 5 is formed in a thin plate shape, the surfacearea thereof can be large, and thus the heat dissipation properties canbe enhanced. In addition, it is preferable that the pressing plate 5 isformed as thin as possible. Accordingly, heat from the heating body 4can be efficiently transferred to the connection portion of the wires,and the time needed for cooling can also be shortened, and therebyaccelerate the solidification of the solder. That is, the productionefficiency can be enhanced.

For the purpose of enhancing heat transfer properties, fins may beprovided on the surface of the pressing plate 5. By providing the finson the surface, the pressing plate 5 is more effectively cooled duringthe cooling performed by the air-cooling fan 6, and thereby acceleratethe solidification of the solder. In the case of providing the fins,fins are not formed on portions that come into contact with the heatingbody 4.

The pressing plate 5 preferably includes a temperature measurement unit.The temperature measurement unit is not particularly limited as long asthe temperature measurement unit can measure a temperature near themelting point of the solder. As an example, a thermocouple or the likemay be employed.

Since the pressing plate 5 includes the temperature measurement unit,the temperature of the connection portion of the wires, that is, themolten state of the solder can be determined. Therefore, in a statewhere the wires are pressed by the heating body 4 via the pressing plate5, when it is determined that the solder is sufficiently melted, theheating body 4 may be separated from the pressing plate 5, and coolingof the connection portion may be started. Furthermore, when it isdetermined that the solder is sufficiently solidified, the pressingplate 5 may be separated from the wires, and a connection process may becompleted.

Similarly, the heating body 4 preferably includes a temperaturemeasurement unit. In addition, it is preferable that a controller whichcontrols the heating member on the basis of the temperature measured bythe temperature measurement unit is provided.

Particularly, in a case where superconducting wires are connectedtogether, in order to prevent a temperature (for example, 300° C. orhigher) at which superconducting properties deteriorate due to excessiveheating of wires from being reached, the temperature measurement unitand the controller are necessary. As the temperature measurement unit,similarly to the temperature measurement unit provided in the pressingplate 5, a thermocouple may be employed.

In the connection process, the connection portion of the wires ispressed by only the pressing plate 5 or by both the pressing plate 5 andthe heating body 4. The pressing force applied to the connection portionneeds to be controlled so as not to break the wires. Particularly in thecase of connecting the superconducting wires, the pressing force iscontrolled (for example, to be 20 MPa or lower) such that the crystalstructure of the superconductor does not break. Since the wires can bepressed at a predetermined pressure by using the air cylinder as thedriver, the breaking of the wires can be suppressed. However, the driveris not limited to the air cylinder, and other drivers such as motordriving may also be employed. In this case, a controller for thepressing force is preferably provided.

In this embodiment, the pressing plate 5 and the heating body 4 areconfigured to approach the holding base 7 or be separated from theholding base 7 by being raised and lowered by the first air cylinder 2or the second air cylinder 3. The holding base 7 may also be configuredto be provided with any driver so that the holding base 7 is elevated bythe driver and the holding base 7 approaches and is separated from thepressing plate 5 and the heating body 4.

The air-cooling fan (cooling member) 6 has a role as a cooling memberthat cools the pressing plate 5 in a state where the pressing plate 5overlaps the upper surface 7 b of the holding base 7. Since the coolingmember that cools the pressing plate 5 is provided, the pressing plate 5can be rapidly cooled, and thus the time needed to solidify the solderof the connection portion is reduced, and thereby the productionefficiency is increased.

As the cooling member, as well as the air-cooling fan 6 used in thisembodiment, a water-cooling type cooling member may also be used.

It is preferable that, in the wire splicing device 1 in this embodiment,a storage unit (not shown) which stores optimal connection conditionsand a control device (not shown) which controls a series of processesaccording to the connection conditions stored in the storage unit arebuilt in. Accordingly, by setting the wires to be connected in the wiresplicing device 1 and inputting various conditions, the connectionprocess can be automatically completed, and thereby stably, easily, andreliably performing the connection of wires.

(Splice Structure)

Next, the wires connected by the wire splicing device 1 of thisembodiment and a splice structure after the connection will bedescribed.

The wire splicing device 1 can be used for connection of various wiresas long as the wires are connected by solder, and is particularlyappropriately used for connection of superconducting wires.

As the superconductor used for the superconducting wires,Bi₂Sr₂Ca₂Cu₃O_(10+δ) (Bi2223) as a Bi-based superconducting wire,REBa₂Cu₃O_(7-X) (RE is a rare-earth element) as an RE-123-basedsuperconducting wire, or the like is known.

The Bi-based superconducting wire is manufactured to have a tape-likestructure by a Powder In Tube method (PIT method) so that a Bi-basedsuperconducting layer is in a state of being coated with an Ag sheathmaterial.

On the other hand, regarding the RE-123-based superconducting wire, astructure is well known in which an oxide superconducting layer islaminated on a tape-like metal base with an intermediate layertherebetween by a film formation method and a thin silver protectionlayer is further formed on the oxide superconducting layer. Moreover, astructure in which a metal tape made of a metal material having goodconductivity such as copper is further laminated on the protection layerwith a solder layer therebetween to function as a stabilizing layer, orthe like is known.

The wire splicing device 1 is applied to the connection of tape-likewires and is thus appropriately used for the above-mentioned Bi-basedsuperconducting wire or the RE-123-based superconducting wire.

As the RE-123-based superconducting wire, for example, one having awidth of 10 mm and a thickness of about 0.1 mm is an exemplary example.

FIG. 2A shows a first splice structure 20 formed by connecting a firstwire 8 and a second wire 9, which are a pair of tape-like wires, withsolder 10. In the first splice structure 20, portions in which an endportion 8 a of the first wire 8 and an end portion 9 a of the secondwire 9 overlap each other, are bonded together by the solder 10, andthereby form a connection portion 20 a.

In a case where RE-123-based superconducting wires having a laminatestructure are used as the first wire 8 and the second wire 9 of thefirst splice structure 20, the superconducting wires are connectedtogether while the protection layers or stabilizing layers which are theuppermost layers of the laminate structures face each other, and therebythe connection portion 20 a having low electrical resistance can beformed.

In addition, when superconducting wires having a width of 10 mm areconnected, the lengths of portions bonded together by the solder in thelongitudinal direction thereof are preferably 10 mm or greater.

FIG. 2B shows a second splice structure 21 formed by connecting a firstwire 11 and a second wire 12, which are a pair of tape-like wires with atape-like connection wire 13.

In the second splice structure 21, an end portion 11 a of the first wire11 and an end portion 12 a of the second wire 12 are disposed facingeach other, and a connection wire 13 is bridged to straddle the endportions. Solder 14 is interposed between the first wire 11 and theconnection wire 13, and between the second wire 12 and the connectionwire 13, and these are bonded by the solder 14, and thereby form aconnection portion 21 a.

In a case where RE-123-based superconducting wires having a laminatestructure are used as the first wire 11, the second wire 12, and theconnection wire 13 of the second splice structure 21, the first wire 11and the second wire 12 are disposed so that the lamination directionsthereof are aligned with each other. Furthermore, the protection layeror stabilizing layer of the connection wire 13 is disposed to face theprotection layers or stabilizing layers of the first wire 11 and thesecond wire 12 and the protection layers or stabilizing layers, and theyare connected together by the solder. Accordingly, the connectionportion 21 a having low electrical resistance can be configured.

Otherwise, a metal wire may also be configured as the connection wire 13while the superconducting wires are used as the first wire 11 and thesecond wire 12.

The form of the solder 10 and 14 used in the first splice structure 20and the second splice structure 21 before being melted may be any of aline form, a tape form, and a paste form. As the solder 10 and 14, awell-known solder may be used. For example, In solder having In as aprimary component, Sn, Sn solder made of an alloy having Sn as a primarycomponent such as an Sn—Ag-based alloy, an Sn—Bi-based alloy, anSn—Cu-based alloy, and an Sn—Zn-based alloy, Pb—Sn-based alloy solder,eutectic solder, low temperature solder, or the like may be employed.These solders may be used singly or in a combination of two or moretypes thereof. Among these, a solder having a melting point of 300° C.or lower is preferably used.

There may be a case where the superconducting properties of thesuperconducting wires may deteriorate due to an effect of heat.Particularly in a case where the melting point of the solder is 300° C.or higher, the wires are heated to 300° C. or higher. Accordingly, in acase of connecting the superconducting wires together, there is concernthat the superconducting properties thereof may deteriorate.

FIG. 3 is a schematic sectional view of the connection portion in a casewhere the above-described first splice structure 20 is formed by thewire splicing device 1 of this embodiment.

The second wire 9, the solder 10, and the first wire 8 are accommodatedin the wire accommodation groove 7 a of the holding base 7 in thisorder, and the connection portion 20 a is pressed by the protrusion 5 aof the pressing plate 5 from above, and is heated by the heating body 4(see FIGS. 1A and 1B) so as to melt the solder 10. Furthermore, theheating body 4 is separated from the pressing plate 5 to solidify thesolder 10, and thereby form the first splice structure 20.

In addition, in a method for forming the second splice structure 21, thefirst wire 11 and the second wire 12 are disposed in the wireaccommodation groove 7 a so that the end portion 11 a of the first wire11 and the end portion 12 a of the second wire 12 face each other, andthe solder 14 is disposed to straddle the first wire 11 and the secondwire 12. The connection wire 13 is disposed and accommodated on thesolder 14 and is pressed and heated by the pressing plate 5 and theheating body 4 from above so as to melt and solidify the solder, andthereby form the second splice structure 21 described above.

(Connection Order)

Next, an operation order of the wire splicing device 1 during theconnection of the wires using the wire splicing device 1 will bedescribed in detail with reference to FIGS. 4A to 4E.

First, the wire splicing device 1 is powered on and heats the heatingbody 4 to increase the temperature of the lower surface 4 a of theheating body 4 to a predetermined temperature (a temperature of equal toor higher than the melting point of the solder). In this initial state,the heating body 4 and the pressing plate 5 may be disposed to beseparated from each other or to be in contact with each other. In a casewhere the heating body 4 and the pressing plate 5 are disposed to be incontact with each other, the pressing plate 5 may be pre-heated andfurther accelerates the melting of the solder, which is preferable.

Next, as shown in FIG. 4A, a pair of wires to be connected areaccommodated in an overlapping manner in the wire accommodation groove 7a of the holding base 7 (wire disposing process). At this time, solderis interposed between the overlapping portions. The pair of overlappingwires and the solder before being melted are called a pre-connectionwire 20A.

In addition, in FIG. 4A, for ease of understanding, a gap is formedbetween the vertical wall of the wire accommodation groove 7 a and theside surface of the wire. However, since the width of the groove and thewidth of the wire are substantially the same, such a gap is not formed.

Next, as shown in FIG. 4B, the first rods 2A and the pressing plate 5are lowered by the first air cylinder 2 such that the pressing plate 5overlaps the holding base 7. In this state, the upper surface of thepre-connection wire 20A is pressed by the protrusion 5 a of the pressingplate 5, and thereby preventing misalignment between the wires of thepre-connection wire 20A (see FIG. 3).

Next, as shown in FIG. 4C, the second rods 3A and the heating body 4 arelowered by the second air cylinder 3 such that the lower surface 4 a ofthe heating body 4 and the upper surface 5 b of the pressing plate 5come into contact with each other. Accordingly, heat of the heating body4 is transferred to the pressing plate 5 and is further transferred tothe pre-connection wire 20A from the protrusion 5 a of the pressingplate 5 so as to melt the solder.

When the solder is melted, the heating body 4 presses the upper surface5 b of the pressing plate 5 by the second air cylinder 3. Therefore, ina state where the pre-connection wire 20A is pressed by not only thepressing plate 5 but also the heating body 4, the solder is melted(pressing and heating process).

The pair of overlapping wires and the molten solder is called a moltensolder wire 20B.

In this embodiment, the pressing plate 5 and the heating body 4 areseparately lowed as shown in FIGS. 4B and 4C. However, they may also besimultaneously lowered.

Next, as shown in FIG. 4D, the second rods 3A and the heating body 4 areraised by the second air cylinder 3. At this time, the pressing plate 5stays on the holding base 7 and continuously presses the upper surfaceof the molten solder wire 20B until the solder solidifies. In addition,by cooling the upper surface 5 b of the pressing plate 5 using theair-cooling fan 6, the temperature of the pressing plate 5 is reduced,and the solidification of the solder is accelerated. Since theconnection portion of the wires is continuously pressed until the soldersolidifies, excess solder does not partially remain in the connectionportion, and a well-finished connection portion can be achieved.

The raised heating body 4 and the pressing plate 5 that stays on theholding base 7 are separated from each other at a sufficient distance atwhich radiant heat from the heating body 4 is not transferred to thepressing plate 5.

When the pressing plate 5 is sufficiently cooled to a predeterminedtemperature, the molten solder of the molten solder wire 20B solidifies(cooling process).

When the pressing plate 5 reaches a predetermined temperature or when apredetermined time has elapsed after cooling is started, the fan isstopped. Furthermore, as shown in FIG. 4E, the first rods 2A and thepressing plate 5 are raised by the first air cylinder 2. Accordingly,the splice structure can be formed, and the splice structure is removed(removing process) to be applied to various products.

In addition, the heating body 4 of the wire splicing device 1 is held ata temperature at which the solder can be melted, and thus a subsequentwire connection operation can be immediately performed.

In addition, in the method for forming the second splice structure 21,the first wire 11 and the second wire 12 are disposed in the wireaccommodation groove 7 a so that the end portion 11 a of the first wire11 and the end portion 12 a of the second wire 12 face each other, andthe solder 14 is disposed to straddle the first wire 11 and the secondwire 12. After the connection wire 13 is disposed on the solder 14, thesecond splice structure 21 can be formed in the same order as theabove-described connection order.

In the wire splicing device 1 of this embodiment, the connection portionof the wires is heated by the heating body 4 via the pressing plate 5 soas to melt the solder, the heating body 4 is thereafter separated fromthe pressing plate 5 (that is, separated from the wires) while anapplication of pressure by the pressing plate 5 is maintained, andheating the wires can be immediately stopped. Accordingly, the wires arenot continuously heated until the heating body 4 has cooled, and thetime required to solidify the solder is reduced. Therefore, the timeneeded to make the connection is reduced.

In addition, in a case where the wire splicing device 1 of thisembodiment is used for the connection of superconducting wires, thedeterioration of the superconducting wires can be suppressed by reducingthe heating time. Furthermore, since the heating time is reduced, in acase where a protection layer made of silver or a silver alloy isprovided on the outer periphery of the superconducting wire or in a casewhere the boundary portion between a silver layer and a solder layer isprovided therein, the diffusion of the solder through the silver layercan be suppressed. Therefore, an increase in the electrical resistanceof the silver layer can be limited.

In addition, in the wire splicing device 1 of this embodiment, heatingthe connection portion of the wires is started or stopped by allowingthe heating body 4 to come in contact with or be separated from thepressing plate 5. Therefore, the heating body 4 can be always held at atemperature at which the solder is melted. Therefore, in a case where asubsequent connection operation is consecutively performed, the heatingbody does not need to be re-heated, and the time it takes to increasethe temperature of the heating body to a temperature at which the solderis melted can be reduced.

INDUSTRIAL APPLICABILITY

According to the embodiment, it is possible to provide a wire splicingdevice, a wire splicing method, and a method for manufacturing a splicestructure which enable connection of wires that exhibit stableperformance with high production efficiency.

DESCRIPTION OF REFERENCE NUMERAL

1: wire splicing device, 2: first air cylinder (first driver), 2A: firstrod, 3: second air cylinder (second driver), 3A: second rod, 4: heatingbody, 4 a: lower surface, 5: pressing plate, 5 a: protrusion, 5 b, 7 b:upper surface, 6: air-cooling fan, 7: holding base, 7 a: wireaccommodation groove, 8, 11: first wire, 8 a, 9 a, 11 a, 12 a: endportion, 9, 12: second wire, 10, 14: solder, 13: connection wire, 20:first splice structure, 20A: pre-connection wire, 20B: molten solderwire, 20 a, 21 a: connection portion, 21: second splice structure

1. A wire splicing method comprising: disposing a tape-like first wireand a tape-like second wire in a holding base so that an end portion ofthe first wire and an end portion of the second wire face each other;disposing solder to straddle the first wire and the second wire;disposing a connection wire on the solder; pressing a heating body tothe first wire, the second wire, and the connection wire via a pressingplate, and pressing together and heating the first wire, the secondwire, and the connection wire so as to melt the solder; keeping thefirst wire, the second wire, and the connection wire pressed together bythe pressing plate; separating the heating body from the pressing plate;and cooling the pressing plate to solidify the solder, and therebyconnecting the first wire and the second wire together.
 2. The wiresplicing method according to claim 1, wherein the first wire, the secondwire, and the connection wire are superconducting wires.
 3. A method formanufacturing a splice structure comprising: disposing a tape-like firstwire and a tape-like second wire in a holding base so that an endportion of the first wire and an end portion of the second wire faceeach other; disposing solder to straddle the first wire and the secondwire; disposing a connection wire on the solder; pressing a heating bodyto the first wire, the second wire, and the connection wire via apressing plate, and pressing together and heating the first wire, thesecond wire, and the connection wire so as to melt the solder; keepingthe first wire, the second wire, and the connection wire pressedtogether by the pressing plate, separating the heating body from thepressing plate; and cooling the pressing plate to solidify the solder,and thereby connecting the first wire and the second wire together. 4.The method for manufacturing a splice structure according to claim 3,wherein the first wire, the second wire, and the connection wire aresuperconducting wires.
 5. The wire connection method according to claim1, wherein the first wire and the second wire are superconducting wires.6. The method for manufacturing a connection structure according toclaim 3, wherein the first wire and the second wire are superconductingwires.